Epilepsy is a disease affecting 1-2% of the population. Currently, the only known cure for epilepsy is surgery, which is much more effective at eliminating seizures arising from the medial temporal lobe compared with the neocortex. The problem with neocortical epilepsy is that the population of neurons underlying each epileptiform discharge varies over time. In addition, the spatial relationship between interictal events and the ictal onset zones, which are critical in defining the region of epileptogenesis, is not well understood and essential to the surgical treatment of epilepsy. Electrophysiological recording methods, although currently the "gold standard" in mapping epilepsy, are inadequate to address these questions based on restrictions due to volume conduction or sampling limitations. Optical recording techniques can overcome many of these limitations by sampling large areas of cortex simultaneously to provide information about blood flow, metabolism and extracellular fluid shifts that are intimately related to excitatory and inhibitory neuronal activity. In fact, optical recordings may actually be more sensitive to certain aspects of epileptic activity than electrophysiologic recordings. The first goal of this study is to examine the shifting spatio-temporal dynamics of the epileptogenic aggregate in both acute and chronic experimental models of in vivo rodent neocortical epilepsy using optical recording of intrinsic signals. Simultaneous electrophysiological and optical measurements will be obtained at varying wavelengths to explore several fundamental questions in neocortical epileptogenesis. The second goal will be to translate these findings into the operating room and map human neocortical epilepsy with the same optical techniques. Outcome following surgical resections to treat neocortical epilepsy will be correlated with the optical maps to determine the utility of intrinsic signal imaging in guiding brain surgery. These experiments will set the groundwork for implementing optical recordings in general clinical practice as a novel technique for mapping and predicting human seizures.